Achieve 60Hz on AOC U3477PQU 34″ Ultrawide Monitor with MacBook Pro 15″ (Late 2013)

The MacBook Pro retina display already comes with a HDMI. so all you have to do is buy a quality HDMI cable and connect them together. Then MacOSX will recognise the display and then you can use it as a normal display.

You are outside "supported" territory with using three screens on that hardware.

• https://support.apple.com/en-us/HT204154 - thunderbolt FAQ
• https://support.apple.com/en-us/HT206587 4k and 5k and beyond

That being said, you can try connecting things and Apple hardware is known to run more displays than the "support" document allows. Usually it's due to driver updates that can still juggle all the connections but that the performance isn't there or you end up with glitches like frozen screens or just not the frame rates Apple likes to see on supported hardware combination.